1. Field of the Invention
This invention relates to a semiconductor package socket and, in particular, to a socket suitable for a semiconductor package wherein a semiconductor chip is mounted on a main surface of a board equipped with a wiring circuit that includes portions to be connected, and wherein flat external connector terminals for connecting to the input/output part of the semiconductor chip are arranged in a constant-pitch lattice-array and are derived and exposed on the back of the board.
2. Description of the Related Art
For example, the structure of a memory card is restricted by such factors as its shape, size, and thickness. Thus, compact mounting of a semiconductor chip that provides memory and control functions is called for. Further, when packaging the semiconductor chip, it is desirable, as much as possible, for the package to be as thin or as compact as the semiconductor chip itself.
Some well-known methods used for compactly mounting the semiconductor chip are the TAB (Tape Automated Bonding) method, the flip chip mounting method and the COB (Chip on Board) method. A typical example of the compact package is given in FIG. 1 which shows a cross-sectional view of the principal structure of the semiconductor package comprising compact circuit board 1 on a main surface of which a semiconductor chip 2 with a memory function, and other electrical parts, are mounted; flat external connector terminals 4 derived from the other main surface of circuit board 1 via through-hole 3, and mold resin layer 5 which coats and seals the mounting region of said semiconductor chip 2. Reference numeral 6 in FIG. 1 represents a bonding wire. The semiconductor package wherein the external connector terminals are derived and exposed on the back (bottom) has the following advantages that make it attractive from the practical point of view:
(a) Face-down mounting is materially possible; PA1 (b) When the semiconductor chip itself is mounted face down, it may be made more compact by eliminating some of the resin mold; and PA1 (c) Compared to that of the semiconductor chip itself, electrical testing of individual products is easier.
However, while the external dimensions of the compact semiconductor package would differ according to the type or capacity of mounted semiconductor chip 2, the number and array form of external connector terminals 4 derived and exposed on the back would also differ. Therefore, when electrically testing and evaluating said compact package, is necessary to prepare dedicated semiconductor package sockets having pin contacts adapted to the number and array form of said external connector terminals 4. Thus, depending on the number and array form of the external connector terminals, dedicated sockets must be prepared beforehand in order to perform electrical testing and evaluation. This means that a large number of dedicated sockets for certain numbers and array forms of the external connector terminal of the semiconductor package is required. However, if the socket for testing is adaptable to many types of semiconductor packages, it is practically difficult to set the size of the compact semiconductor package close to that of the semiconductor chip.
Further, if external connector terminals 4 derived and exposed on the back of said compact semiconductor package are arranged in a constant-pitch lattice-array, the connecting terminals on the surface of the mounted wiring board can be standardized. Standardization of said connecting terminals then lead to the standardization of circuit design for mounted wiring boards, thus making it possible to expand the versatility of mounted wiring boards.
An object of the present invention is to provide a semiconductor package socket suitable for electrical testing of compact semiconductor packages having external connector terminals arranged in a constant-pitch lattice-array.
A further object of this invention is to provide a semiconductor package socket which is highly reliable for electrical testing and evaluation of compact semiconductor packages having external connector terminals arranged in a constant-pitch lattice-array.
A still further object of the present invention is to provide allow-cost semiconductor package socket through standardization.
A yet still further object of the present invention is to provide a semiconductor package socket which may be used regardless of the type of the compact semiconductor package wherein external connector terminals are arranged in a constant-pitch lattice-array.
Yet another object of the present invention is to provide a semiconductor package socket wherein it is possible to standardize the circuit design of the mounted wiring board and expand the versatility of the mounted wiring board.